In this scenario, a host PC is connected to both a corporate network (via NIC #1) which allows internet access as well as a private network (via NIC #2).

2 Steps total

Step 1: Understanding the network configuration

The corporate network is setup to assign a DHCP address in the range of 10.0.x.x with subnet mask 255.255.0.0 to NIC #1. The default gateway (router) address is 10.0.0.1.

Figure 1. In this scenario, a multi-NIC controller is connected to both a corporate network (with internet access) and a local private network.

Step 2: Configuring NIC's

Following the guidelines above, we can configure NIC #2, attached to the private network, with a static IP outside of the 10.0.x.x subnet range. While it might be acceptable to use an address in the 10.1.x.x range, as it is in a different subnet, it is possible that other 10.x.x.x IP addresses are used for additional corporate servers, etc. Therefore, it is safer to use the 192.168.x.x range for the private network.

Table 1. This table shows one possible IP address configuration for the system shown in Figure 1 above. Notice that the two NICs connect to different subnets, and that only one Default Gateway address is specified.

It is important to leave the default gateway blank on the NIC #2 settings for the host machine, as they should only be communicating within the local subnet (there are no gateways connected). In this way, only the NIC #1 default gateway will be used, which is what we want in order to access the internet from the host.